Exhaust muffler means



April 14, 1959 L. 'M. MORRISH ETAL 2,881,852

' EXHAUST MUFFLER MEANS Filed June 14. 1956 INVENTORS. [ma m if omsfi BYd flyd 6 77/2 11 0Q ATTORNEY United States Patent EXHAUST MUFFLER MEANS Leonard M. Morrish and Lloyd E. Muller, Flint, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application June 14, 1956, Serial No. 591,328 1 Claim. (Cl. 181-57) This invention relates to mufiler means in general and more particularly to through-flow mufller means for silencing the noise of engine exhaust gases.

Engine exhaust noises are generally silenced within mufiler means which include bafile members and tortuous passages for diverting the normal flow of exhaust gases in order to separate out such objectionable sounds. This in turn restricts the flow of exhaust gases through the mufiler means and produces back pressures having an adverse efiect upon the efiicient operation of the engine means.

It is here proposed to provide a through-flow exhaust muffler for use with internal combustion engines, air compressors and the like, which includes means for dissipating or mufiling exhaust gas noises Without the normal resultant back pressures. It is proposed to provide a mufller member having a through-flow passage formed by separate inlet and outlet conduits joined together by an expansion chamber. This serves to break the flow conduit into components of smaller length and has an eifect upon their resonant character. It is further proposed to provide resonator chambers about the flow conduits immediately preceding and following the expansion chamber. Such chambers may communicate with either or both the expansion chamber or the flow conduits by suitable acoustical coupling means. Nonetheless important is the provision of baffie means disposed across the expansion chamber between the inner ends of the flow conduits for diverting or baflling the normal flow of exhaust gases around the bafile means and through openings formed therein and axially oiiset from the normal flow path. The baflling of exhaust gases within the expansion chamber has little material eifect as regards back pressure since the openings are greater in size than the flow passage within the conduits.

The proposed mufiler means may be made so that it may be accommodated within less space and may be formed as a cylinder, oval or other shape, and may have the flow conduits aligned or offset without an appreciable sacrifice of acoustical benefits.

In the drawings:

Figure 1 is a cross-sectional view of the proposed muffier means.

Figure 2 is a cross-sectional view of the bafile plate within the proposed mufiler means as seen in the plane of line 2-2 of Figure 1, looking in the direction of the arrows thereon.

Figure 3 is an enlarged fragmentary section of the communication means between the flow conduit and one of the chambers of the proposed muffler means as here taken in the plane of line 3-3 of Figure l.

The embodiment of this invention as shown by the drawings comprises a muffier having a casing or shell 12, here oval in shape, closed by end plates 14 and 16 and having separator or divider walls 18, 20, 22 and 24 therein to form resonator chambers 26, 28, 30 and 32 as well as expansion chamber 34. Flow conduits 36 and 38 are extended through the divider walls, which are flanged as shown to receive the conduits or tubes, and are in open 2,881,852 Patented Apr. 14, 1959 communication with the expansion chamber 34. Conduit 36 provides an inlet passage 40 and conduit 38 an outlet passage 42 for the flow of exhaust gases through mufiler 10. Coupler or adapter members 44 and 46 are received over the outer ends of the conduits 36 and 38 to provide means for connecting the muffler within an exhaust system.

Bafile means 48 is provided within expansion chamber 34 in the path of exhaust gases which would otherwise flow across the chamber between conduits 36 and 38. Such means includes a baffle plate 50 secured across the expansion chamber transversely of the flow conduits and having openings 52 and 54 formed therethrough near the side walls of the shell 12 and axially olfset from the flow conduits 36 and 38. The openings 52 and 54 are larger than the outlet of conduit 36 and do not restrict the flow of gases between the two parts 56 and 58 of the expansion chamber 34. The edges of the baffle plate are turned over about the openings, in the direction of the flow of exhaust gases, as is shown at 60, and the baffle plate is slightly concave as shown at 62 to better direct and handle gases received thereagainst.

An opening 64 is formed within wall 20 and a conduit 66 is secured therein to provide an acoustical coupling 68 connecting the expansion chamber 34 to the resonator chamber 28.

Other acoustical couplings 70, 72 and 74 are provided between the flow conduits 36 and 38 and the resonator chambers surrounding the conduits. The acoustical couplings include louvers 76 struck from the conduits as best shown by Figure 3. The coupling 72 further includes a shielding conduit 78 concentrically disposed about the louvered section of the outlet conduit 38 to change the character of such coupling.

In operation, exhaust gases are received within the inlet passage 40 of conduit 36 and flow straight through to the expansion chamber 34. Acoustical couplings 70 and 68 are disposed to receive exhaust gas noises and such noises are dissipated within resonator chambers 26 and 28. The exhaust gas is diverted by bafile plate 50 towards the outer edges of the plate where it flows through openings 52 and 54 formed therein. Because of the size of the bafile plate openings the exhaust gas flow is not restricted but merely diverted to separate out the sound waves traveling therewith. The gases then converge towards the outlet passage 42 formed by conduit 38 to flow past the other resonator chambers 30 and 32 which further filter out objectionable noises by means of the acoustical couplings 72 and 74.

While the illustrated mufiler is oval in shape such shape does not contribute to the proposed mufiler means to any great extent as would limit the mufiler housing or casing 12 being other than oval. Likewise the conduits 36 and 38 while shown to be axially aligned might be otfset without adverse effect.

We claim:

Vehicle engine exhaust mufiler means comprising a housing having end walls, a plurality of intermediate walls transversely of said housing and in parallel spaced relation to said end walls, the first of said intermediate walls and one of said end walls defining a first resonator chamber therebetween and the second of said intermediate walls and said first intermediate wall defining a second resonator chamber therebetween, an expansion chamber formed by said second intermediate wall and the third of said intermediate walls and centrally of said housing, an inlet conduit extending through said end wall and said first and second resonator chambers and opening centrally into said expansion chamber, said conduit having a plurality of louvered accesses opening into said first resonator chamber, an acoustical coupling conduit secured to said second intermediate wall and offset from said inlet conduit and extending into said second resonator chamber for acous- 3 tical ly connecting said ex ansion chamber and said second resonator chamber, a baifie plate disposed in said expansion chamber and having a pair of openings therein, said openings being offset from said inlet conduit and each of sufiicient size to permit unrestricted flow of gas therethrough, said baflle plate being concave in the direction of gas flow through said expansion chamber, the fourth of said intermediate walls and said third intermediate wall defining a third resonator chamb'ertherebetween and said fourth intermediate wall and the other of said end walls defining a fourth resonator chamber therebetween, an outlet conduit extending through said third and fourth resonator chambers and through the other of said end walls and opening centrally of said expansion chamber and aligned with said inlet conduit, said outlet conduit having a plurality of louvered accesses formed therein and opening into said third and fourth resonator chambers, and an acoustical shielding conduit secured to said fourth intermediate wall and extending into said third resonator chamber and concentrically disposed about said outlet conduit and about said louvered accesses opening into said third resonator chamber, said resonator chambers, said acoustical conduits, said louvered accesses and said concave baffie plate altering the acoustical character of the exhaust gases flowing therethongh to rnuflie and dissipate any noises transmitted thereby from the vehicle engine.

References Cited in the file of this patent UNITED STATES PATENTS 1,023,225 Shlosberg Apr. 16, 1912 1,024,688 Lewis a Apr. 30, 1912 2,218,063 Munzer Oct. 15, 1940 2,220,866 Jensen Nov. 5, 1940 UNITED STATES PATENT OFFICE v CERTIFICATE OF CORRECTION Patent No, 2,881,852 April 14-, 1959 Leonard M Morrish et air It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

vColumn 4, list of references cited under the heading, "UNITED STATES PATENTS", add the" following:

2 717,048 Deremer w r 1 Sept, 6, 1955 2,337,299 Norblitt et al.- Dec 21, 1943 Signed and sealed this llth day of August 1959,

(SEAL) Attest:

KARL H.a AXLINE ROBERT C. WATSON Attesting Oflicer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,881,852 April 14, 1959 Leonard M, Morrish et all.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, list of references Cited,- under the heading, "UNITED STATES PAIENTS" add the following:

2 ,717,048 Deremer MY e Sept, 6, 1955 2,337,299 Norhlitt St 31;,- D604 21, 1943 Signed and sealed this 11th day of August 1959,

(SEAL) Attest:

KARL AXLINE ROBERT c. WATSON Attesting Officer Commissioner of Patents 

